The present invention relates generally to operations performed in conjunction with a subterranean well and, in an embodiment described herein, more particularly provides an expandable liner and associated methods of regulating flow through tubular structures in a well.
A wellbore may intersect multiple formations or zones from which it is desired to produce fluids. It is common practice to utilize well screens and gravel packing where the formations or zones are unconsolidated or poorly consolidated, in order to prevent collapse of the wellbore or production of formation sand. Thus, fluid production from one zone may flow through one well screen while production from another zone may pass through another well screen.
It is frequently desirable to be able to individually control the rate of production from different zones. For example, water encroachment or gas coning may prompt a reduction or cessation of production from a particular zone, while production continues from other zones.
Conventional practice has been to use a valve, such as a sliding sleeve-type valve, or a downhole choke to regulate fluid flow from a particular zone. However, where well screens are also utilized, it is often impractical, costly and inconvenient to use conventional valves or chokes to regulate fluid flow through the screens. Therefore, it is an object of the present invention to provide an improved method of regulating fluid flow through well screens. It is a further object of the present invention to provide methods and apparatus for regulating fluid flow through various tubular structures in a well.
In carrying out the principles of the present invention, in accordance with an embodiment thereof, a specially configured expandable liner is utilized in regulating fluid flow through a tubular structure in a wellbore. The flow regulating systems and methods described herein also permit economical, convenient and accurate control of production through individual well screens and screen assemblies.
In one aspect of the present invention, a screen assembly including multiple well screens is installed in a wellbore. An expandable liner is then inserted into the screen assembly. The liner is expanded by any of various methods (e.g., inflation, swaging, etc.), so that the liner is sealingly engaged with the interior of the screen assembly. For example, the liner may be sealingly engaged straddling a well screen, so that fluid flow through the well screen must also pass through an opening formed through a sidewall of the liner.
Expansion of the liner may also be used to control the rate of fluid flow through the screen assembly. For this purpose, a sealing material may be disposed externally on the liner between an inflow area of a well screen and the opening formed through the liner sidewall. By squeezing the sealing material between the liner and the screen assembly, a flow area formed between portions of the sealing material is reduced.
By retracting the liner inwardly away from the screen assembly, the flow area may also be increased, thereby increasing the rate of fluid flow through the well screen. Thus, the flow rate through the screen may be increased or decreased as desired by retracting or expanding the liner within the screen assembly.
The exterior of the liner which contacts the interior of the screen assembly may be configured to provide further regulation of fluid flow. For example, the sealing material may have one or more channels formed therein or therethrough. The channels may be tortuous to provide flow choking. Plugs may be provided to reduce the number of channels through which fluid may flow.
Tools for expanding and retracting the liner are also provided by the present invention. One such tool includes a sensor sensing a parameter, such as flow rate, temperature, pressure, etc., of the fluid flowing through a well screen. This permits the effect of expansion or retraction of the liner to be evaluated downhole for an individual well screen, or for multiple screens.
These and other features, advantages, benefits and objects of the present invention will become apparent to one of ordinary skill in the art upon careful consideration of the detailed description of representative embodiments of the invention hereinbelow and the accompanying drawings.